1. Field of the Invention
The present invention relates to structures constructed by ultrasonic welding and, in particular, to an improvement in a structure constructed by ultrasonic welding for accommodating an electric apparatus having contacts, such as a relay or the like, which is hermetically sealed.
2. Description of the Prior Art
There are known prior art techniques for constructing a case for accommodating an electric apparatus or the like by ultrasonic welding. For example, Japanese Utility Model Publication No. A-Sho 56-104022 discloses such a technique.
However, these known techniques had problems in that when the accommodating case was constructed by ultrasonic welding, a part of the synthetic resin deposited on a joint portion, which did not contribute to welding, i.e., welding refuse, penetrated from the joint portion into the interior of the accommodating case. For this reason, there was a risk that the welding refuse was deposited, for example, on the contacts of the electric apparatus accommodated within the case, which caused a contact defect in the electric apparatus.
In addition, these known techniques had a problem in that if the welding refuse existed between different members forming the accommodating case, ultrasonic energy, which is desirably concentrated into the joint portion, was dispersed also on the welding refuse existing between the different members, which made the ultrasonic welding imperfect.